Notes

The LNER would often denote major modifications with a slash. E.g. B16/2 is a modified B16.
Occasionally such modifications would be so substantial that a completely new class number would be
given (eg. an A3 is a modified A1). Modifications of the same class typically share the same webpage.

Thompson and Peppercorn both reused class numbers. Reused class numbers are prefixed with the
engineer's name.

Acknowledgments

Thank you to Ray Fisher for writing most of the introductory text for each wheel arrangement.